Difference between "pull over" and "pull away"

Pull over is an unambiguous (clear-cut) command to pull to the curb (that is, to the edge of a paved street) or onto the shoulder of a road, and stop.

The phrase pull away has multiple uses. One could order a driver of a parked vehicle to "Pull away now," meaning for you to maneuver the vehicle out of its parking spot and resume driving. Or one could say, "Pass that vehicle, pull away, and return to this lane," meaning to safely pass a vehicle and when clear of it return to your lane. (Driving instructors may say things like the above; I can't say whether any examiners would do so.)